Telephone voice silencer



NOV. 12, 1935. L 5, SCHER 2,020,970

TELEPHONE VOICE SILENCER Filed Oct. 29, 1934 INVENTOR Lou IS 5'. Sher Patented Nov. 12, 1935 UNITED STATES PATENT OFFICE 12 Claims.

This invention relates to voice silencers or mufflers particularly adapted for use in connection with telephones where it is desired to hold confidential conversation even though others are present in the same room.

The present invention is an improvement of my Patent #l,399,083 of December 6, 1921, which enjoyed considerable commercial success. In addition to the objects and advantages set forth in that patent the present invention seeks to provide improved means to absorb the sound waves which do not enter the mouth piece of the telephone.

Another object of this invention is to provide a muffler which may be used interchangeably either with the so called desk type of telephone or with the hand set type now in more common vogue, and being readily adapted for use by right or left handed users.

A still further object is to provide means in the muffler whereby blasting (i. e. sharp and harsh noises produced by certain voice formations) is eliminated so that sound which enters the mouth piece is smooth, articulate and clear.

A still further object of the invention resides in the provision of relatively larger sound absorbing surfaces whereby a greater portion of the sound radiations are absorbed within the device.

A further object of the invention is to provide a mufiler, which though it readily retains its shape, is made of some such material as soft rubber as a further aid to the absorption of the sound radiations and to minimize reflected sounds, as well as to be conformable to various sizes and shapes of transmitters and adapted for angular adjustment of the receiver to suit the needs of the particular individual user.

In order to obtain a clearer understanding of the invention and the purposes thereof, reference is made to the accompanying drawing which illustrates a preferred embodiment of the invention, described in the following specification, and in which:-

Fig. 1 is a. front view in quarter section of a muffler constructed in accordance with the invention.

Fig. 2 is a vertical sectional view thereof through the medial center line and shown as applied to a desk type telephone.

Fig. 3 is a front view of the device as applied to a hand set type of telephone.

Fig. 4 is a fragmentary sectional view of the fitting employed to close the mouth piece opening of the muflier when used as in Fig. 3.

Fig. 5 is an inside view, partially in section, of an alternate form of voice absorption unit.

Referring to the drawing in greater detail the muffler body ll] of some material such as soft rubber is preferably formed with two lateral ex- 5 tensions II and i2 and a depending extension l3 so that in effect it is T shaped to provide the T shaped voice chamber l4. Each end of the T forming the body is preferably provided with a detachable sound absorbing unit l5.

Each unit I5 is preferably made of a light spun metal container having an outer wall l6 and inreaching opening H, the opening being circumscribed by a flange l8 engageable in the circumferential groove IS in each end of the body. These sound absorbing units may be identical and interchangeable with each other.

Within the hollow of each unit is preferably positioned a disc of dense, compacted felt 20 provided with holes, perforations or the like 2|. A disc of more porous felt 22 having perforations 23 is preferably placed to overlay the felt disc 20 and be positioned in the throat of its respective body extension. So these latter discs may be more securely held in position the throats of the T shaped body are preferably outwardly flared as shown.

The body In is also provided with a flanged opening 24 in the middle of its rear portion and into this opening there is preferably inserted a thin metal tube 25 into which the telephone mouthpiece 26 is adapted to be inserted. For reasons later apparent, the tube 25 is provided with holes such as 21.

Opposite the flanged openings 24 and preferably upwardly directed there is provided an opening 28 into which the user may speak, this opening being provided with the usual rim 29 shaped to accommodate the lips of the user.

It will be noted from Fig. 2 that the lips of the 40 user are directed right into the mouth piece of the telephone and the direct sound waves, therefore, enter therein. Those radiations of the sound which do not enter the mouth piece either are absorbed in the sound absorbing units I5 directly or are deflected from the inner walls of the voice chamber l4 until so absorbed. In this manner little or no sound may escape from the mufiler.

The sound absorbing qualities of the felt is well known and to enhance these qualities the perforations 23 and 2| are provided inasmuch as the small chamber formed by each perforation individually acts to effectively dissipate any tendency to deflect sound radiations entering therein. 55

Sometimes a harsh sound or forced breath is emitted into the device and may not be readily and quickly enough absorbed in the muffler. This causes what is known as blasting and will cause a distorted sound to be transmitted to the remote telephone receiver. To obviate this, the holes 21 are provided in the transmitter supporting tube 25. These holes which communicate the voice chamber with the outside relieve the compression of air within the silencer. This compressed air and jumbled air waves in passing through the holes 21 first enter the annular chamber defined by the mouth piece and the tube 25, and then strikes against the front face of the transmitter. In this manner the air follows a tortuous path sufficient to dissipate this sound.

The above is descriptive of the muffler as used with a desk type telephone. When used with a hand set telephone, one of the lateral sound absorbing units is removed and the vacated throat of the muffler is utilized to receive the transmitter portion 30 as shown in Fig. 3. Either the right or left hand unit may be removed for this purpose according to the requirements of the individual user. Arranged in this manner the ear of the user is adapted to be placed against the receiver portion 3 I the hand, on the grip 32; and the lips against the rim 29 where they are in proper position in relation to the transmitter opening 33.

The broken line showing, in this figure, of the hand set phone, illustrates the facility with which the ear piece 3| may be adjusted to suit the shape and size of the head of the user, the pliability of the mufiler body permitting positive retention of the transmitter 30 and in all posi tions effectively sealing the throat from the outside.

When used in this manner the tube 25 is removed from the muffler and a chambered member 34 inserted into the opening 24 (Fig. 4). While this member may be provided with sound absorbing material, in this instance it is shown as provided with holes 35 in the inner wall 36 of the member and with holes 31 in staggered relation to the holes 35 in the outer wall 38. These holes are so placed as to produce in effect a soundtrap so only air may escape to the outside to prevent the blasting above mentioned. This also relieves compression and aids breathing.

Although one manner of forming the sound absorbing units has been described, it is of course conceivable, that the felt discs may be arranged in different ways, all seeking to enhance the absorption qualities of the units. In addition to the manner already described the unit may be made up in the following manner. The outer layer of felt 40 and an intermediate layer 4| may preferably be made of dense, compacted felt and the inn-er layer 42 of a more porous felt. The inner layer being perforated at 23 as hitherto and the intermediate layer cut out as shown to provide a chamber 43 between the inner and outer layers. It can be seen from this arrangement that any sound which may pass through the inner layer will be in part absorbed in the chamber 43 and in part absorbed by the outer layer 40 thus effectively preventing the escape of sound outside the mufiler.

From the foregoing it will be seen that a simple device for the purpose has been disclosed in the preferred form of its embodiment, but it is not desired to restrict the details to the exact construction shown, it being obvious that changes, not involving the exercise of invention may be made without departing from the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A voice silencer comprising a body having a chamber provided with a telephone mouthpiece opening, an opening to which the mouth of the user may be applied, lateral extensions and a down reaching extension, and a sound absorbing unit removably positioned in each of said extensions.

2. A voice silencer comprising a body having a T-shaped chamber, an extension at each extremity of the chamber, and a sound absorbing unit removably positioned in each of said extensions.

3. A voice silencer comprising a shape retaining pliable body having a chamber provided with more than two extensions, and a sound absorbing unit removably positioned in each of said extensions.

4. A voice silencer comprising a T-shaped hollow body, and sound absorbing means positioned at each extremity of the body.

5. A voice silencer comprising a T-shaped hollow body, and sound absorbing means positioned at each extremity of the body, said sound absorbing means comprising a container, a dense perforated sound absorbing member therein, and a relatively porous perforated sound absorbing 80 member overlying said dense member.

6. In a voice silencer, a hollow body having open lateral extensions, an open downreaching extension, an opening to which the mouth of the user may be applied, and a telephone mouthpiece opening; and sound absorbing means in each of the mentioned extensions.

7. In a voice silencer, a hollow body having open lateral extensions, an open downreaching extension, an opening to which the mouth of the user may be applied, and a telephone mouthpiece opening; sound absorbing means in each of the mentioned extensions, and a tube having holes positioned in the telephone mouthpiece opening.

8. A voice silencer comprising a body having a 45 chamber provided with lateral extensions and a downreaching extension, and a sound absorbing unit removably positioned in each of said extensions, whereby the unit in either of said lateral extensions may be selectively replaced by the transmitter portion of a hand set telephone.

9. In a sound muffler having a. chambered body provided with lateral extensions, an opening to which the mouth of the user may be applied and an opening substantially opposite said mouth opening; means in the extensions and in the last mentioned opening selectively removable to adapt the muffler for use on either a desk type or hand set telephone transmitter.

10. In a sound muffler having a chambered bocly provided with lateral extensions, an opening to which the mouth of the user may be applied and an opening substantially opposite said mouth opening; means in the extensions and in the last mentioned opening selectively removable for replacement therefor of the transmitter of a telephone.

11. A voice silencer comprising a body having a chamber provided with lateral extensions and a downreaching extension, an opening to which the mouth of the user may be applied, and a telephone mouthpiece opening, a sound absorbing unit for each extension, each unit having an annular flange and each extension having a circumferential groove for reception of and removable en- 15 gagement with said flange, whereby the unit in either of said lateral extensions may be selectively replaced by the transmitter portion of a hand set telephone.

12. A voice silencer comprising a body having a chamber provided with lateral extensions and a downreaching extension, an opening to which the mouth of the user may be applied, a telephone mouthpiece opening, and a sound absorbing unit interlockingly and removably positioned in the extremities of each of said extensions, whereby the unit in either of said lateral extensions may be selectively replaced by the transmitter portion of a hand set" telephone, said sound absorbing units comprising a rigid container enclosing a plurality of three (3) sound absorbing members, one of said sound absorbing members being relatively porous and the other two of said sound absorbing members being relatively dense, with one of the dense sound absorbing members being positioned between the other dense member and the porous member and being provided with a central 1o chamber.

LOUIS S. SCHER. 

